On 04/24/17, Miken said the following...
Please correct me if I'm wrong... but PDP is programmed by switches. That means there is not any possibility to type in any semantically more complex sentences. It's not that I wouldn't be able to comprehend in a bunch of time on how to handle it. But it's too far away from my understanding of the World. And I'm sorry for it. My nature is more language orientated than mathematical. I'm trying to "talk" to machines. And it's not really a natural thing to talk in ASM. Whatever I hope I didn't insult You or so.
Wow, there's a lot of misinformation floating around here.
PDP-series machines were produced by Digital Equipment Corporation (and its successors).
The PDP line of processors was actually a family of machines. The PDP-6 and PDP-10 were mainframe-class machines; the -11 was a minicomputer, and the -8 and -7 were often used in industrial control applications. Most of the PDP family machines were word-oriented; the -11 was byte-oriented (that is, bytes could be individually addressed by the CPU, as opposed to whole words of
memory with special instructions to manipulate bytes inside of the word). The PDP-1 was the first in the line and was arguably NOT mainframe-class. The -6 and -10 used a 36-bit word (chosen to be competitive against mechanical calculators of the era, which had 9 significant digits: 36-bits are
sufficient to store 9 4-bit BCD digits). The -11 had a 16-bit word; the -7
had an 18-bit word and the -8 had a 12-bit word.
The PDP-7 is perhaps most notable for being the machine that Ken Thompson originally wrote Unix on (after Bell Labs pulled out of the Multics project that targeted the 36-bit GE-645 machine - another word-oriented
mainframe-class machine).
The most famous of the PDP series of computers were undoubtedly the -10, on which much of the early ARPANet and Internet work was done, and the -11, on which much of the early Unix work was done. Ken and Dennis Ritchie moved Unix to the PDP-11 fairly quickly. While some of the very early PDP machines did have front-panel switches, most often one interacted with them via terminals connected to serial ports. The VAX series of computers were introduced as a successor to the PDP-11 and used a 32-bit word and 32-bit virtual address space. They ultimately took over much of Digital's 36-bit business as well.
Hercules is a mainframe emulator, where it is understood that "mainframe"
means "IBM mainframe". It implements the z/Architecture instruction set and emulators for many mainframe peripherals. z/Architecture is the successor to the S/390 instruction set, which succeeded the S/370, which succeeded the
S/360 which succeeded a number of early IBM machines such as the 7094, which was a 36-bit word-oriented machine. System/360, introduced in the 1960s, was byte-oriented with 32-bit registers and, I think, a 20- or 24- bit address space (I could be wrong). 370 was a 32-bit machine; z/Arch is a full 64-bit machine. When most people refer to "mainframes" they mean IBM and compatible mainframes using one of these instruction sets; most of IBM's traditional competitors in the space are gone. The only remaining competing architecture seems to be Unisys 1100-series machines, which are themselves successors of
CDC machines. IBM also had a number of mid-range system options, including System/36 et al and AS/400, but these are not instruction-set compatible with their mainframe systems. Note that most mainframes also support terminal access; one can even run Unix on some of them. VM/370 -> VM/CMS -> VM/ESA -> z/VM is probably the most familiar environment for mainframe access for most modern users; the other popular options were the timesharing option for the batch MVS operating system (MVS/TSO succeeding, if I recall, TSS/360). Modern mainframes often run Linux under z/VM.
Anyway, the point is that DEC, IBM, Unisys/CDC and GE/Honeywell/Bull
mainframes are all distinct systems and most are accessed interactively.
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